Display device and manufacturing method thereof

Abstract

It is an object to provide a manufacturing method by which display devices can be manufactured in quantity without degrading the characteristics of thin film transistors. In a display device including a thin film transistor in which a microcrystalline semiconductor film, a gate insulating film in contact with the microcrystalline semiconductor film, and a gate electrode overlap with each other, an antioxidant film is formed on a surface of the microcrystalline semiconductor film. The antioxidant film on the surface of the microcrystalline semiconductor film can prevent a surface of a microcrystal grain from being oxidized, thereby preventing the mobility of the thin film transistor from decreasing.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a display device in which a thin film transistor is used at least in a pixel portion.[0003]2. Description of the Related Art[0004]In recent years, technology that is used to form thin film transistors using semiconductor thin films (with thicknesses of from several tens of nanometers to several hundreds of nanometers, approximately) formed over substrates having an insulating surface, for channel formation regions, has been attracting attention. Thin film transistors are applied to a wide range of electronic devices such as ICs or electro-optical devices, and prompt development of thin film transistors that are to be used as switching elements in image display devices, in particular, is being pushed.[0005]As a switching element in an image display device, a thin film transistor in which an amorphous semiconductor film is used for a channel formation region, a thin film transistor in whic...

AI Technical Summary

Benefits of technology

[0021]In the present invention, an antioxidant film is formed on a surface of a microcrystalline semiconductor film and thus oxidation of a surface of a microcrystal grain can be reduced, thereby preventing the mobility of a thin film transistor from decreasing.

[0022]With use of a microwave plasma CVD apparatus with a frequency of 1 GHz or more, a deposition rate of a microcrystalline semiconductor film can be increased, and mass productivity of a display device including a thin film transistor including the microcrystalline semiconductor film can be improved.

[0023]In addition, a crystallization process of a semiconductor film after formation of the semiconductor film can be omitted, so that a system-on-panel of the display device can be achieved without complicating a manufacturing process of the thin film transistor.

Problems solved by technology

However, the thin film transistor using a polycrystalline semiconductor film for a channel formation region requires a more complicated process than the thin film transistor using an amorphous semiconductor film for a channel formation region because of crystallization of the semiconductor film.

Thus, there are problems such as a reduction in yield and an increase in cost.

Further, there is a problem in that a surface of a crystal grain of a semiconductor is easily oxidized.

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